Both Mitt Romney and Barack Obama face an uphill battle convincing voters that they share faith values that are similar to a largely Judeo-Christian America, according to a newly released book exploring the link between religion and the presidential election.

"There are some interesting parallels between Obama's and Romney's situations," said Public Religion Research Institute Director of Research and Co-founder Daniel Cox. "Most people don't know their religious faiths."

Cox wrote a chapter about Americans' perceptions of Obama's faith in the newly released Religion and the American Presidency.

In the book he reveals that only four in 10 Americans believe that Obama is a Christian. Similarly, only four in 10 know that Romney is a Mormon.

Additionally, Cox said both Romney and Obama are commonly viewed as having religious beliefs that the majority of Americans say are "more religiously dissimilar than similar" to their own beliefs.

Americans, the book finds, favor a president with strong religious beliefs that mirror their own.

"The ability of politicians to develop a rapport and trust among voters by sort of having a common faith or common values that's very helpful," Cox said.

Therefore, the uncertainty surrounding both candidates' faith may hinder their abilities to connect with voters, he expressed.

The book Religion and the American Presidency is a compilation of data showing religion's influence on American voters' perceptions of U.S. presidents and presidential candidates.

The book is edited by George Mason University Professor of public policy Mark Rozell and Gleaves Whitney of the Hauenstein Center for Presidential Studies. Rozell will further discuss the book with a panel of political experts and religion writers on Jan. 30 at the National Press Club.